Exhaust manifold attachment apparatus and method for fabricating same

ABSTRACT

A flexible connector apparatus for decoupling vibrations, for example, along the components of an internal combustion engine exhaust system. The flexible connector apparatus is provided for connecting first and second components in the exhaust system, and includes a bellows for accommodating relative movement between the first and second components. The flexible connector apparatus includes an attachment construction which enables weldless, gasketless connection of the bellows to at least one of the first and second components. The flexible connector apparatus may include a liner tube structure having inlet and outlet liner tubes. An alternative construction incorporates a multi-ply bellows in the absence of a liner structure.

This application is a divisional application, under 35 U.S.C. 120 ofU.S. patent application Ser. No. 08/838,601, filed Apr. 10, 1997, U.S.Pat. No. 5,957,504.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to connectors for joining the ends ofsuccessive lengths of pipe or conduit and/or connecting a pipe orconduit to a housing or other mounting surface wherein the connectionwill be exposed to axial transverse and bending vibrations. Inparticular, the present invention relates to connectors for joiningpipes to one another or to other structures in exhaust systems forvehicles.

2. The Prior Art

It is well known that, in vehicle exhaust systems, particularly thosefor heavy duty vehicles, such as large trucks or earth moving equipment,the internal combustion (i.c.) engines produces significant amount ofvibration in the exhaust system. Operation of the motors at continuousspeeds for prolonged periods of time can, especially, produce what areknown as harmonic vibrations which can cause significant deflections inextended lengths of exhaust pipe and at locations where such pipes aremounted to structures such as brackets, engine manifolds, and the like.Repeated deflections and vibration along the exhaust pipe system can, inturn, cause the structures to weaken with time and ultimately fail.Further, such harmonic vibrations can also be transmitted through theexhaust pipes to the mountings of the pipes, promoting the loosening ofthe mountings, which can result in the sudden displacement of one ormore components of the exhaust system, with the potential for bothpersonal injury and equipment damage.

In addition to the vibrations caused by the operation of the motor ofthe vehicle, an exhaust system is also subjected to various tension,compression and bending forces, which also arise during the operation ofthe vehicle. While individual exhaust system components could be madestronger and more massive to resist failure by fatigue, suchconstructions would be undesirable due to weight considerations.Further, by making individual elements stiffer, the vibrations aremerely transmitted throughout the exhaust system to the mountings orother components and are not reduced or eliminated. Accordingly, it isdesirable to isolate the exhaust system, or at least components of thesystem, from such vibrations and forces.

It is known that if the pipes of an exhaust system are divided andseparated by non-rigid connections, rather than being constructed ascontinuous extended lengths, the development of harmonic vibrations fromthe motor is precluded or reduced. Such non-rigid connections can beadvantageously employed to absorb other tension, compression and bendingforces, apart from and in addition to the motor vibration.

It is therefore desirable to provide a connector for joining a length ofexhaust pipe, to another pipe or to a mounting, such as an enginemanifold, which connector joins the components in a non-rigid fashionand is capable of absorbing tension, compression, and bending forces, aswell as the vibrational forces, without transmitting them from oneexhaust system component to another.

Typical prior art flexible connectors often require welds at both ends,in order to achieve a strong, substantially fluid-tight connectionbetween the connector and the other exhaust system components to whichthey are attached. It would be desirable to avoid the use of weldswhenever possible, as such welds take time to perform, adding to theinstallation time of the connector, and increasing the overall assemblytime of the vehicle or apparatus to which they are being attached.

In addition, such welds are often difficult to place properly, oftenrequiring additional complexity in the construction of the flexibleconnector, in order to provide working space for accomplishment of theweld. Still further, there is always the possibility of a small flaw inthe weld, leading to possible leakage of harmful exhaust gases, and/orthe introduction of a physical weakness in the structure of the flexibleconnector attachment, leading to the expenditure of additional time fordouble-checking the quality of each weld being performed.

In some instances, a weld is undesirable, and in order to provide forsome form of sealing, gaskets must be positioned at the interfacebetween the flexible connector and the exhaust manifold or othercomponent to which the connector is being attached. Such gaskets whichare usually made from mica coated stainless steel, for example, couldbegin to experience leakage shortly after installation, and, presumingan exhaust manifold pressure in the vicinity of 4.5 psig, could have aleakage rate of over 0.5 liters per minute.

It would be desirable to provide an alternative to welding for themanufacture and/or installation of flexible connector apparatus, whichwould be less expensive, require less intensive examination uponcompletion and/or have an enhanced degree of reliability and/ormanufacturability than welding techniques.

It would be desirable to provide a flexible connector apparatus and amethod and apparatus for the manufacture and installation of it, whichwould employ fewer welds.

It would also be desirable to provide a weldless connection between aflexible connector apparatus and a component, such as an exhaustmanifold, which does not rely upon the use of gaskets, which maydeteriorate with use, and which could experience leakage when in use.

These and other objects of the invention will become apparent in view ofthe present specification including claims, and drawings.

SUMMARY OF THE INVENTION

The present invention comprises, in part, a flexible connector apparatusfor connecting first and second components of a fluid conduit system,such as an exhaust system for an internal combustion engine. Theapparatus comprises a bellows member, having an axis, first and secondends, and at least two substantially uniform convolutions disposedsubstantially adjacent the first of the two ends; and a flange member,positioned in circumferentially surrounding relationship to the bellowsmember, axially between the at least two substantially uniformconvolutions of the bellows member.

The flange member includes at least one attachment element, operablyassociated with the flange member and configured for attachment of theflange member to one of the first and second components of the fluidconduit system.

The attachment element further is configured to capture one of the atleast two substantially uniform convolutions axially between the flangemember and the one of the first and second components of the fluidconduit system, for forming, upon completed attachment of the flangemember to the one of the first and second components, a substantiallyfluid-tight weldless seal between one of the at least two substantiallyuniform convolutions of the bellows and the adjacent end of the bellowsmember, and the one of the first and second components.

The axially opposite end of the bellows member is operably configuredfor attachment at least indirectly to the other of the first and secondcomponents, for forming a substantially fluid-tight connectiontherewith, toward enabling the substantially fluid-tight transportationof fluid from the one of the first and second components, through theflexible connector apparatus, to the other of the first and secondcomponents.

The flexible connector apparatus further comprises, in one embodiment, aliner tube structure insertably received within the bellows member. Theliner tube structure, in turn, may comprise a first liner tube memberhaving a radially outwardly extending annular flange at one end thereof,the first liner tube member being insertably received in the first endof the bellows member, such that at least a portion of one of the atleast two substantially uniform convolutions is positioned axiallybetween the flange member and the radially outwardly extending annularflange member, such that upon capture of the convolution between theflange member and the one of the first and second components, theradially outwardly extending annular flange member is also capturedthereby; and a second liner tube member, telescopically engaged with thefirst liner tube member and insertably received within the bellowsmember, at a position distal to the first end of the bellows member,being operably configured for attachment at least indirectly to theother of the first and second components, for forming a substantiallyfluid-tight connection therewith, toward enabling the substantiallyfluid-tight transportation of fluid from the one of the first and secondcomponents, through the flexible connector apparatus, to the other ofthe first and second components.

A first substantially resilient spacer member is radially disposedbetween the telescopically engaged first and second liner tube members.Axially spaced first and second stop members, may be operably associatedwith the first and second liner tube members, respectively, for axiallyengaging the first spacer member therebetween, and limiting extensiveaxial movement of the first and second liner tube members relative toone another.

An end cap member may be provided, circumferentially surrounding aportion of the second end of the bellows member and a portion of thesecond liner tube member distal to the first liner tube member.

A second end cap member may be provided, circumferentially surrounding aportion of the first end of the bellows member and a portion of thefirst liner tube member distal to the second liner tube member, aportion of the second end cap member in turn being circumferentiallysurrounded by the flange member.

In an alternative embodiment of the invention, the bellows member isfabricated from at least two telescopically engaged tubular members, sothat at least an innermost one of the tubular members overlaps others ofthe tubular members and, at least at the end proximate the flangemember, extends axially beyond at least one other of the tubularmembers.

An end cap member may be provided, circumferentially surrounding aportion of the member, a portion of the end cap member in turn beingcircumferentially surrounded by the flange member.

In another embodiment of the invention, the convolution which isdisposed between the flange member and the proximate end of the memberis formed from a layer of no more than two telescopically engagedtubular members.

The present invention also comprises a method for manufacturing aflexible connector apparatus, for connecting first and second componentsof a fluid conduit system, such as an exhaust system for an internalcombustion engine, comprising the steps of:

forming a first tubular member, having two ends;

forming a flange member, having an aperture therethrough having aninside diameter which is substantially equal to but greater than anoutside diameter of the first tubular member;

configuring at least one attachment element on the flange member toenable attachment of the flange member to one of the first and secondcomponents;

inserting the first tubular member into the aperture of the flangemember, to a position proximate one of the two ends of the first tubularmember;

forming a plurality of at least two annular substantially uniformconvolutions in the first tubular member, each such convolution havingan outside diameter greater than the outside diameter of the firsttubular member,

subsequent to formation of the at least two substantially uniformconvolutions, the flange member being positioned between andsubstantially abutted by two of the at least two substantially uniformconvolutions.

In one embodiment of the method, the method further comprises the stepsof:

inserting a liner structure into the first tubular member afterformation of the at least two substantially uniform convolutions; and

mechanically connecting the liner structure to the first tubular member.

The step of inserting a liner structure further comprises the steps of:

forming a first liner tube member having a diameter, which is, less thanthe diameter of the first tubular member;

forming an second liner tube member having a diameter which is less thanthe diameter of the first tubular member and predominantly less than thediameter of the first liner tube member;

telescopically inserting the second liner tube member into the firstliner tube member, so that a portion of the first liner tube memberoverlaps a portion of the second liner tube member.

The step of inserting a liner structure may further comprise the stepof:

positioning at least a first substantially resilient spacer memberradially between the first liner tube member and the second liner tubemember.

The method may further comprise the step of:

preparing the end of the first tubular member, proximate the flangemember, so that, upon attachment of the flexible connector apparatus toone of the first and second components, one of the convolutions becomesentrapped and compressed between the flange member and the one of thefirst and second components, to form a substantially fluid-tight sealtherebetween, toward precluding escape of fluid therefrom.

Preferably, the step of inserting the first tubular member into theaperture of the flange member, to a position proximate one of the twoends of the first tubular member further comprises the step of:

inserting an end cap member over the first tubular member, a portion ofthe end cap member being radially enclosed by the first tubular memberand the flange member.

Alternatively, the method may further comprises the steps of:

forming one or more second tubular members, having a diameter less thanthe diameter of the first tubular member; and

inserting the one or more second tubular members into the first tubularmember, so that at least the first tubular member overlaps the one ormore tubular members, and at least at the end proximate the flangemember, extends axially beyond at least one of the one or more tubularmembers.

The step of forming a plurality of at least two substantially uniformconvolutions further comprises the step of:

forming the convolution which is to be disposed between the flangemember and the proximate end of the member from a layer of no more thantwo telescopically engaged tubular members.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a side elevation, in partial section, of a flexible connectorapparatus, according to one embodiment of the invention, prior toassembly to an exhaust manifold.

FIG. 2 is a side elevation, in partial section, of a flexible connectorapparatus, according to one embodiment of the invention, subsequent toassembly to an exhaust manifold.

FIG. 3 is an end elevation of a flange member suitable for use as acomponent of any of the embodiments of the flexible connector apparatusof the present invention.

FIG. 4 is a side elevation of the flange member of FIG. 3.

FIG. 5 is a side elevation, in partial section, of an inlet tube of aflexible connector apparatus according to the embodiment of FIG. 1 ofthe present invention.

FIG. 6 is a side elevation, in partial section, of an outlet tube of aflexible connector apparatus according to the embodiment of FIG. 1 ofthe present invention.

FIG. 7 is a side elevation, in section, of a mesh ring of a flexibleconnector apparatus according to the embodiment of FIG. 1 of the presentinvention.

FIG. 8 is a side elevation, in section, of an end cap of a flexibleconnector apparatus according to the embodiment of FIG. 1 of the presentinvention.

FIGS. 9-11 are schematic illustrations of steps in the process offorming a bellows for a flexible connector apparatus according to theembodiment of FIG. 1 of the present invention.

FIGS. 12-15 are schematic illustrations of steps in the process ofassembling the inlet and outlet tubes for a flexible connector apparatusaccording to the embodiment of FIG. 1 of the present invention.

FIGS. 16-17 are schematic illustrations of steps in the process ofassembling the bellows/flange member structure to the assembled inletand outlet tubes for a flexible connector apparatus according to theembodiment of FIG. 1 of the present invention.

FIG. 18 a is a side elevation, in partial section, of a flexibleconnector apparatus, according to another embodiment of the invention,prior to assembly to an exhaust manifold.

FIGS. 18 b is an end elevation of a flange member suitable for use witha flexible connector apparatus of the embodiment of FIG. 18 a.

FIG. 19 is a fragmentary side elevation, in section, of a flexibleconnector apparatus, according to still another embodiment of theinvention.

FIG. 20 is a fragmentary side elevation, in section, of a flexibleconnector apparatus, according to still yet another embodiment of theinvention.

FIG. 21 is a sectional view of an apparatus for forming the convolutionsin a tube, which has a flange member fitted thereon.

FIG. 22 is a sectional view of the apparatus of FIG. 21, after pressurehas been applied to the water within the tube to be formed.

FIG. 23 is a sectional view of the apparatus of FIGS. 21-22, when theblade pairs are moved so as to enlarge the bulges into convolutions.

FIG. 24 is a perspective view of a modified convolution formingapparatus, configured for forming a plurality of bellows/flange memberunits at one time, which are then separated by severing of their commontube.

FIG. 25 is a side elevation, in section, of the apparatus of FIG. 24.

FIG. 26 is an end elevation of a convolution forming apparatus accordingto any of FIGS. 21-25, showing the pivoting action of the blades inunison, relative to one another.

DETAILED DESCRIPTION OF THE DRAWINGS

While this invention is susceptible of embodiment in many differentforms, there is shown herein in the drawings and will be described indetail several specific embodiments, with the understanding that thepresent disclosure is to be considered as an exemplification of theprinciples of the invention and is not intended to limit the inventionto the embodiments illustrated.

FIGS. 1 and 2 illustrate flexible connector 10 according to oneembodiment of the invention. Several of the components which make upflexible connector 10, are also shown individually in FIGS. 3-8, andinclude flange member 12 (having central aperture 14 and bolt holes 16),inlet tube 18 (having outwardly turned flange 20 and inwardly turnedbead 22), outlet tube 24 having outwardly turned bead 26, mesh rings 28and 30, end cap 32, and bellows 34. Mesh rings 28, 30 may be formed fromcompressed steel mesh, ceramic wool, or the like, according to knowntechniques, and may even be impregnated with materials such as graphite,vermiculite and/or other friction-reducing material. In a preferredembodiment of the invention, mesh rings 28 and 30 are substantiallyidentical.

Depending upon the requirements of the particular installationapplication, the flange may have a different shape, other than generallyrectangular, and/or may have fewer bolt holes. In addition, while meshring 28 will be present in typically all applications, in someembodiments mesh ring 30 may not be employed.

Bellows 34 is preferably formed according to the process illustrated inFIGS. 9-11. A piece of sheet metal material is rolled into a cylindricaltube 40 and welded. According to the requirements of the particularinstallation application, a second sheet of material may be formed intoa tube 42 having a slightly greater or lesser diameter and thentelescopically inserted into or fitted around tube 40 to form acomposite tube 44. Additional, smaller diameter tubes may besuccessively inserted, as well. If a number of layers are desired forthe bellows tube, as an alternative to using plural telescoping tubes,the bellows tube may be formed as a spiral coil, having a number ofturns. Other methods of providing multiple tube layers may also be used.

The composite tube 44 is then hydroformed, according to otherwise knowntechniques, to produce substantially uniform convolutions 46, and totalbellows structure 34. In typical hydroforming of a bellows, a piece oftube (actually two or more telescopically arranged tubes) are placedinto a hydroforming device, and plugged at their ends. A typicalhydroforming apparatus has a plurality of blades, set in pairs, whichpivot together like a set of jaws. In other hydroforming apparatus, thepairs of blades are arranged to close together in a non-pivoting linear(e.g., vertical or horizontal) motion, like the components of a press.Each blade of each pair will have a semicircular cutout, so that when apair of blades is closed around the tube, the cutouts form an aperture,which will have a diameter slightly greater than the initial greatestoutside diameter of the unformed tube. After the several pairs of bladeshave closed around the tube, and been clamped into place, asubstantially incompressible fluid material, such as water. Since thewater is essentially incompressible, the tube yields, bulging in thelocations between the spaced apart pairs of blades.

The pairs of blades are all interconnected and configured for axialmovement, in pairs. For example, the axially outermost blade pairs canbe moved, such as by a hydraulic cylinder, toward one end of the tube.The movement of the various blade pairs is coordinated, so that thereduction in the length of the spaces between the blade pairs isaccomplished in a uniform manner. Movement of the blades begins afterthe tube has been “bulged” after introduction of the water. The blades“grab” the tube bulges, forcing the bulges to become radially larger andaxially shorter, growing into the evenly spaced convolutions seen in thefinished product.

However, in prior art bellows hydroforming procedures and prior artbellows constructions, a simple sequence of uniform convolutions isformed. In the present invention, at a selected location on thecomposite tube, which would be otherwise between the last convolution 48at one end and the penultimate convolution 50 adjacent to the lastconvolution 48, a flange member 12 is fitted over composite tube 44,prior to the hydroforming step, to form bellows 34 and compositebellows/flange member structure 52. In order to accommodate the flangemember during the hydroforming step, one pair of blades, which wouldotherwise form the indentation between the last and penultimateconvolutions, is omitted or shifted aside.

During the hydroforming step, the portion of composite tube 44, which isencircled by flange member 12, will conform to fit against the innersurface of aperture 14.

The process of hydroforming is illustrated in a highly schematic mannerin FIGS. 21-26.

FIGS. 21-23 show an apparatus for forming a single bellows tube/flangemember combination. Tube 44, with flange member 12 is inserted into thedevice, the pairs of blades 80, 81 are closed, nose pieces 83, 84 areinserted into the ends of tube 44, and sealed so that no water canescape from between either of nose pieces 83, 84, and the tube. Someform of position holding device, such as a spacer member (not shown),will position the flange during the convolution formation process. Tube44 is then filled with water through one of the nose pieces, e.g. nosepiece 84. As pressure is applied to the column of water in the tube, theblades constrain portions of the tube. The unconstrained portions of thetube 44 bulge radially outwardly, slightly.

The blade pairs 80, 81 and the end block pairs 86, 87 are then moved, ina coordinated manner, to “squeeze” the bulges. One of nose pieces 83, 84is moved (see arrow, FIG. 23), to follow the corresponding end of thecontracting tube 44, and the convolutions are formed. The ends of tube44 which project beyond blocks 86, 87, are affixed, to prevent the endsof tube 44 from being pulled in toward the center of the apparatus, asthe blade pairs are moved. One method of affixing the ends 44 would beto swage the ends to create flares, which will axially fix the ends (seedotted line in FIG. 22).

Spacers 94, 96 are provided on the blades and on the blocks,respectively, so that as axial pressure is placed, for example from theleft to the right on the end block, the convolutions begin to form.Since the blade pairs will move varying distances, those on the rightwill have the least distance to move, and the corresponding convolutionswill form first, although all the convolutions will be formed during thesingle hydroforming process. Since the final spacing of the blades ismore or less uniform, as defined by the spacers, the final convolutionswill be more or less uniform, including those on both sides of theflange.

FIGS. 24, 25 illustrate an alternative construction of the convolutionforming device, in which several (e.g., 3) bellows tube/flange memberunits are formed, using a common tube. After forming of theconvolutions, and removal of the formed tube from the device, the tubeis cut into three separate sections, typically at the locations wherethe necks are formed by blocks 86. The spacers are omitted for clarityof illustration.

FIG. 26 illustrates the relative pivoting of the separate units of theblade and block pairs. When the pairs are closed a latch or clamp 90 isused to hold the pairs in closed position, against the pressure exertedby the tube as a result of the water pressure.

While one general type of hydroforming is shown schematically anddescribed herein, other forming techniques may be used. However, thegeneral process described has the advantage of more or lesssimultaneously forming substantially uniform convolutions on either sideof a flange in a single manufacturing step, enhancing themanufacturability and reducing the cost of the overall component.

After the hydroformed bellows/flange member structure 52 is removed fromthe hydroforming machine, bellows/flange member structure 52 willtypically undergo various adjustments and finishing processes, in orderto prepare the structure 52 for installation.

The remaining neck of composite tube 44 (which usually has a length ofabout 0.625 inches) may be further processed, in one of the followingmethods, among others: a) complete removal from convolution 48; b)trimming to a length of about 0.030 inches, which might typically becrushed down during the process of attachment to the manifold; and c)rolling radially inwardly and around and back into the bellows. Excessneck is then trimmed from the opposite end of composite tube 44.

Inlet tube 18, outlet tube 24, and mesh rings 28, 30 are assembledaccording to the procedure shown in FIGS. 12-15. First, mesh ring 28 isinserted into inlet tube 18, and fitted against bead 22. Preferably, theouter diameter of mesh ring 28 is such that there is a slightly forcedfit between mesh ring 28 and the inner surface of inlet tube 18. Next,outlet tube 24 is inserted into inlet tube 18 (from the right to left,the direction of the arrow, as seen in FIG. 13). Mesh ring 28 therebybecomes axially enclosed by beads 22 and 26.

Optional mesh ring 30 may then be fitted onto outlet tube 24, again,preferably with a slightly forced fit, until it abuts bead 22. Then, theportion of outlet tube 24, which is downstream of mesh ring 30, istypically expanded outwardly, such as by swaging, to an increaseddiameter, as shown in FIGS. 1, 2 and 15. The assembled components formliner tube structure 54.

In order to improve the fluid dynamics and reduce possible noise whichmay be created at the leading edge of outlet tube 24, the liner tubestructure 54 may be provided with a shroud 92, shown in phantom in FIG.17, which would extend radially inwardly from the inner surface of inlettube 18, to help smooth the flow of fluid through the flexibleconnector.

The final assembly of bellows/flange member structure 52 and liner tubestructure 54, to form flexible connector 10, prior to its subsequentinstallation to another component, such as an exhaust manifold, is shownin FIGS. 16-17. Liner tube structure 54, comprising inlet tube 18,outlet tube 24, and mesh rings 28, 30, is inserted into bellows/flangemember structure 52. Thereafter, end cap 32 is fitted onto the free endof the bellows/flange member structure 52, and forcibly sized radiallyonto the overlapping bellows 34 and outlet tube 24, to form a snugmechanical connection between outlet tube 24 and the bellows 34, at 56.One function of end cap 32 is to provide some protection to bellows 34against externally directed abrasion or moving objects, which coulddamage or even puncture the bellows.

Although a two-piece (inlet tube/outlet tube) liner is shown in theembodiment of FIGS. 1-17, other kinds of liner structure, within thebellows tube, can be employed, if desired. Other examples include, butare not limited to, a three-piece liner (two end tubes connected by athird outer or inner tube overlapping or overlapped by the two endtubes), a single piece of straight tube, a metal wire braided sleeve(often used for acoustic purposes and/or to limit the amount ofextension of the bellows), or a spiral wound tube, all of whichseparately are known in the art. Since these other kinds of linerstructures are inserted after formation of the bellows/flange structure,the assembly after formation of the liner, is substantially the same aspreviously described.

In addition, the beads 22, 24, which are shown to be 90° turns of theends of the liner tubes, may be substituted with flanges turned agreater or lesser amount, for example in the range from 45° to a full180°turn, or with annular rings welded onto the ends of the liner tubesor the like, or omitted altogether.

Alternative embodiments may have a flange at both ends of the bellowsstructure. This may readily be accomplished by placement of flanges nearopposite ends of the unformed bellows tube, and formation of theconvolutions in the manner discussed previously, using a suitablyconfigured convolution formation set-up, followed by insertion of aliner structure according to the needs of the particular application.

FIG. 2 illustrates the final assembly procedure, during which theflexible connector apparatus 10 is affixed to another exhaust vehiclecomponent, in this case, an exhaust manifold 58. Annular depression 59,which will have a depth which preferably will be approximately the sameas or slightly less than the thickness of flange 20 and which will havea diameter which will be at least as great as or slightly larger thanthat of flange 20, will be formed into exhaust manifold 58, either aspart of the original manufacturing process for manifold 58, or as alater machining step. Flexible connector apparatus 10 is affixed, suchas by bolts (not shown) through bolt holes 16 which will mate withcorresponding blind bolt holes (not shown) in exhaust manifold 58. Otherforms of fastening may be employed, if desired.

Alternatively, depression 59 could be placed in the opposing face offlange 12. In that case, it is important that the diameter of thedepression 59 is less than the diameter of convolution 48, so that theseal can be formed.

As the bolts are tightened down, for example, to the degree of tightnesswhich would be used in prior art coupler installations using gaskets,convolution 48 will become substantially completely flattened betweenexhaust manifold 58 and flange member 12, until seals are formed betweenflattened convolution 48 and exhaust manifold 58, and between flangemember 12 and flattened convolution 48 of bellows 34, respectively,which are substantially more effective in terms of fluid tightness, andmore simply obtained than prior art connector constructions, all withoutthe need for a separate gasket component. At the opposite end offlexible connector apparatus 10, if a fluid tight connection has beenformed between bellows 34 and outlet tube 24 by the sizing of end cap32, then outlet tube 24 is simply connected, typically by a simple weldor braze, to the downstream exhaust system component (not shown). If nofluid tight seal has been formed between outlet tube 24 and bellows 34,then such a seal is formed at the time of connection to the downstreamexhaust system component, using conventional assembly techniques.

If desired, the last convolution on apparatus 10 may be precompressed,prior to mounting to the exhaust manifold or other component to which itis being attached.

The embodiment of FIGS. 1-17 is shown having a liner tube structure, inwhich the inlet tube 18 has a greater diameter than, and insertablyreceives, outlet tube 24. It is understood that, if desired by therequirements of the particular installation application, the relativeorientations could be reversed, while still being within the scope ofthe present invention. That is, the inlet tube could be provided with alesser diameter, and be insertably received within, the outlet tube,with the inlet tube still being provided with a flange 20, as in theillustrated embodiments.

In addition, it is to be understood that the entire apparatus 10, which,as shown in FIGS. 1-17 is intended to be connected, for example, to anexhaust manifold, in which the flow of fluid is from right to left (inFIG. 2), could be installed in the reversed orientation, for example, tothe inlet of a muffler, in which case, the inlet tube would actually bethe outlet, and the flow through the apparatus would be from left toright, as the apparatus is seen in FIG. 2.

The flexible connector apparatus of the present invention provides asubstantially fluid-tight seal at the interface between the bellows andthe exhaust manifold, without the need for a weld or braze. In addition,such a connection can be made, if desired, without the need for apacking or seal positioned between the bellows and any clamping device,such as the flange member, and the surface of the exhaust manifold towhich the flexible connector is being attached. This enables theconnection to the exhaust manifold to be accomplished more quickly, moresimply, and less expensively, than in prior art flexible connectorconstructions.

In addition, in prior art flexible connector constructions, instead of aradially extending flange at the end of the inlet tube, only a necktypically would be provided which would have to have a substantialthickness, in order to accommodate the weld or braze which wouldtypically be used to connect the tube to the flange. Usually the weldingprocess would result in warping of the flange, which, in turn, wouldrequire the use of a gasket, to enhance the sealing of the connection.The present invention permits the inlet tube end and flange to be muchsmaller and thinner, since the material no longer has to be sized toaccommodate a weld. The invention also obviates the need for a sealinggasket.

In the embodiment of FIGS. 1-17, the inlet and outlet tubes, are linertubes, serving to thermally insulate the bellows from the exhaust gases.The inlet and outlet liner tubes also serve to isolate the bellowschemically from the corrosive exhaust gases. The inlet and outlet tubes,and mesh members, in cooperation with the bellows, accommodates axialextension and compression of the flexible connector apparatus, resultingfrom relative movement of the exhaust manifold (or other upstreamcomponent) and the downstream component (such as a tailpipe structure).The mesh members serve to provide resilient absorption of shock andvibration, which might otherwise occur during over-compression, andoverextension of the connector apparatus. In addition, the mesh ringsaid in dampening and decoupling lateral vibrations in the exhaustsystem. In addition, the inlet and outlet tubes and the spacer radiallyin between, provide support for the flexible connector structure.

In some applications, it may be desirable to provide a flexibleconnector construction, which is substantially self-supporting, as thatterm is understood by those of ordinary skill in the art (i.e., noadditional support for the connector for some stated number of tubediameters' distance from the connection to the exhaust manifold), butwhich eliminates the need for the inlet and outlet tubes, which, whileadding to the strength and loadcarrying capacity of the flexibleconnector apparatus, simultaneously add to the flexible connectorapparatus weight, cost and complexity. Such structure may not bedesirable or particularly advantageous in situations where weight orcost is critical or where available installation space is at a premium.

Such an alternative flexible connector apparatus 60 of the invention isshown in FIGS. 18 a and 18 b. The inlet and outlet tubes, and the meshrings are omitted. Bellows 62 is preferably formed from a plurality (2or more, 3, preferably) of layers of tube material, which may betelescoped, closely fitted tubes, or if a number of layers are desiredfor the bellows tube, as an alternative to using plural telescopingtubes, the bellows tube may be formed as a spiral coil, having a numberof turns. Other methods of providing multiple tube layers may also beused. A tube having a single thick layer could be used if desired insome applications. The formation of the bellows, with the flange member64, axially enclosed by convolutions 66 and 68, is accomplished byhydroforming techniques, substantially the same as those employed withrespect to the embodiment of FIGS. 1-17, in that flange member 64 isslipped onto the unformed tubes, prior to formation of at least theendmost convolution 68.

Not all of the “plies” of tubes forming the bellows 62 will becoextensive. While all of the plies may have aligned ends at the“downstream” end of flexible connector apparatus 60 (as illustrated), atthe upstream end (i.e., adjacent the flange member location), the end(s)of the radially innermost tube or tubes stop to form a cylindrical neck72, which is surrounded by the flange member 64. The innermost ply ortube 70 (or possibly the two innermost plies or tubes) proceed(s)upstream to form convolution 68. That is, the end convolution adjacentthe flange will be made from, typically, one (or more) fewer plies thanthe remaining convolutions, and the plies which make up the endconvolution will be the innermost one or two plies (although in theinstance of a tube having more than three plies, the numbers of plieswhich are shortened and the number which make up the last convolutionmay be varied). The reduction in the number of plies permits a strongbellows-only connector structure to be created, but still permits theflattening of the last convolution to provide the sealing between theflange, the convolution and the component to which the coupling is beingattached.

While it is preferred that at least the innermost ply form the endmostconvolution, the other plies if any of the endmost convolutionpreferably are the next adjacent plies, though others may be used.

The mounting of flexible connector apparatus 60 to an exhaust manifold(such as manifold 58 from the previous embodiment, minus the annulardepression 59) is similarly accomplished by bolting down flange member64 to an exhaust manifold or other structure having bolt holes alignablewith bolt holes 63 of flange member 64, and an aperture alignable withcentral aperture 65, of flange member 64.

The multi-ply bellows 62 of the flexible connector apparatus of FIGS. 18a and 18 b provides accommodation of extension, compression, and lateralmovements, with a substantially self-supporting feature arising from theincreased stiffening of the bellows structure, all without theadditional cost, complexity and weight of the inlet and outlet tubeliner structure of the prior embodiment.

Although not specifically illustrated, it is understood that theembodiment of FIGS. 1-17 can also be constructed having a bellowsfabricated from more than two telescoped tubes, and having an endconstruction, in which the end convolution adjacent the flange has fewerplies than the remaining convolutions.

FIG. 19 shows another alternative embodiment of the invention, which issubstantially similar to the embodiment of FIGS. 1-17, and whereinelements having functions and structures similar to that of likeelements in the first embodiment are provided with like referencenumerals, augmented by a prime (′). As it is understood that theapparatus of FIG. 19 is symmetrical about a central axis designatedC_(L), only the “upper” half of the flexible connector apparatus 10′ isshown, in section.

Apparatus 10′ is substantially identical to apparatus 10, both instructure, and in method of fabrication, except that an upstream end cap72 is provided, for giving some protection to the exterior of bellows34′. A cylindrical portion 74 of end cap 72 is captured between flangemember 12′ and bellows 34′, when the convolutions 48′ and 50′ of bellows34′ are formed by the previously described hydroforming process.Typically the lesser diameter “neck” of end cap 72 will have an axiallength which is less than the thickness of flange member 12′, so that itwill not extend entirely to convolution 48′. Once end cap 72 has beenpositioned, and bellows 34′ formed, the remainder of the formation andassembly process for flexible connector apparatus 10′ is the same asdescribed with respect to apparatus 10. End cap 72 provides protectionfor the bellows, and also provides lateral support for the bellowsitself, as described in further detail with respect to the followingembodiment.

FIG. 20 shows another alternative embodiment of the invention, which issubstantially similar to the embodiment of FIGS. 18 a and 18 b, andwherein elements having functions and structures similar to that of likeelements in the first embodiment are provide with like referencenumerals, augmented by a prime (′). As it is understood that theapparatus of FIG. 20 is symmetrical about a central axis designatedC_(L), only the “upper” half of the flexible connector apparatus 60′ isshown, in section.

Apparatus 60′ is substantially identical to apparatus 60, both instructure, and in method of fabrication, except that an upstream end cap72′ is provided, for giving some protection to the exterior of bellows62′. A cylindrical portion 74′ of end cap 72′ is captured between flangemember 64′ and bellows 62′, when the convolutions 66′ and 68′ of bellows62′ are formed by the previously described hydroforming process.Typically, the neck portion of end cap 72′ will have an axially lengthwhich is less than the thickness of flange member 64′, so that it willnot extend entirely to convolution 68′. Once end cap 72′ has beenpositioned, and bellows 62′ formed, the remainder of the formation andassembly process for flexible connector apparatus 60′ is the same asdescribed with respect to apparatus 60.

End cap 72′, as discussed with respect to the other embodiments,provides external protection for the bellows convolutions in thevicinity of the ends of the bellows. In addition, and particularly withrespect to the bellows-only embodiment, the end cap(s) provide lateralsupport for the flexible connector apparatus. Especially in thebellows-only embodiment, the portion of the bellows (particularly thesmaller diameter portion or “core”) nearest the ends can become exposedto substantial bending forces, which could lead to over-bending of thebellows, leading in turn to permanent excessive deformation and/orfatigue failure from repeated extreme bending. Accordingly, the end capprovides a limit to the amount of bending that the bellows can undergo.

In some embodiments, the diameter of the convolutions and the shape ofthe end caps will be established so that upon installation, the bellowswill have a compressive preload, so that endmost convolutions will beprompted into contact, at locations not at the greatest diameter, to theinner surface of the end caps, to provide further support for theflexible connector apparatus. In addition, the preloading of the bellowsconvolution against the end cap(s) prevents “buzzing” or rattling whichmight otherwise occur, during operation of the machine to which theflexible connector apparatus is attached.

In alternative embodiments of the invention, a braided metal sleeve,such as are known in the art, may be substituted for or used in additionto the end cap(s) 72, 72′. The placement of such a metal braid wouldoccur after the formation of the convolutions, including thosesurrounding the flange.

The foregoing description and drawings merely explain and illustrate theinvention and the invention is not limited thereto except insofar as theappended claims are so limited, as those skilled in the art who have thedisclosure before them will be able to make modifications and variationstherein without departing from the scope of the invention.

What is claimed is:
 1. A method for manufacturing a flexible connectorapparatus, for connecting first and second components of a fluid conduitsystem, such as an exhaust system for an internal combustion engine,comprising the steps of: forming a first tubular member, having alongitudinal axis and further having two ends, an inside diameter and anoutside diameter; providing a flange member, having an aperturetherethrough and having an inside diameter which is greater than theoutside diameter of the first tubular member; the aperture further beingdefined by a continuous, non-interrupted rim, configuring at least oneattachment element on the flange member to enable attachment of theflange member to one of the first and second components; inserting thefirst tubular member into the aperture of the flange member, to aposition located near one of the two ends of the first tubular member;forming a plurality of at least two annular substantially uniformconvolutions in the first tubular member, each of said at least twoconvolutions comprising a circumferentially and radially extending foldof the bellows material, said fold returning at least partially uponitself toward said longitudinal axis, each of such convolutions havingan outside diameter greater than the outside diameter of the firsttubular member, positioning the flange member prior to the formation oftwo of the at least two substantially uniform convolutions between, andsubsequently substantially abutting, each of said two uniformconvolutions.
 2. The method according to claim 1, further comprising thesteps of: inserting a liner structure into the first tubular memberafter formation of the at least two substantially uniform convolutions;and mechanically connecting the liner structure to the first tubularmember.
 3. The method according to claim 2, wherein the step ofinserting a liner structure further comprises the steps of: forming anfirst liner tube member having a diameter, which is, less than thediameter of the first tubular member; forming an second liner tubemember having a diameter which is less than the diameter of the firsttubular member and predominantly less than the diameter of the firstliner tube member; telescopically inserting the second liner tube memberinto the first liner tube member, so that a portion of the first linertube member overlaps a portion of the second liner tube member.
 4. Themethod according to claim 3, wherein the step of inserting a linerstructure further comprises the step of: positioning at least a firstsubstantially resilient spacer member radially between the first linertube member and the second liner tube member.
 5. The method according toclaim 1, further comprising the step of: preparing located near the endof the first tubular member, the flange member, so that, upon attachmentof the flexible connector apparatus to one of the first and secondcomponents, one of the convolutions becomes entrapped and compressedbetween the flange member and the one of the first and secondcomponents, to form a substantially fluid-tight seal therebetween,toward precluding escape of fluid therefrom.
 6. The method according toclaim 1, wherein the step of inserting the first tubular member into theaperture of the flange member, to a position proximate one of the twoends of the first tubular member further comprises the step of:inserting an end cap member over the first tubular member, a portion ofthe end cap member being radially enclosed by the first tubular memberand the flange member.
 7. The method according to claim 1, furthercomprising the steps of: forming one or more second tubular members,having a diameter less than the diameter of the first tubular member;and inserting the one or more second tubular members into the firsttubular member, so that at least the first tubular member overlaps theone or more second tubular members, and at least at the end of the firsttubular member located neat the flange member, extends axially beyond atleast one of the one or more second tubular members.
 8. The methodaccording to claim 1, wherein the step of forming a plurality of atleast two substantially uniform convolutions further comprises the stepof: forming the convolution which is to be disposed between the flangemember and the end of the first tubular member from a layer of no morethan two telescopically engaged tubular members.